One test plot was experimentally burned each year, one was burned every three years, and one was left completely intact.

每试验性地毁一块试验地， 每毁一块，还有一块完无损。

So currently, the US Food and Drug Administration only allows doctors to use fecal transplants experimentally for battling one of the toughest gut infections — antibiotic-resistant Clostridiodes difficile.

，美国食品药品监督管理局（FDA）只允许医生试验性地通过粪菌移植对付一种最严重的肠道感染疾病——耐抗生素梭状芽胞杆菌感染。